Typically, an axial gap is provided between a turbine shroud and the outer wall of a gas path duct at ambient temperatures, to allow for thermal expansion of the duct and/or the turbine shroud at engine operating temperatures. The magnitude of such thermal expansion can be predicted, and the gap sized, so that thermal expansion generally seals the gap to prevent leakage through the gap.
However, the seal is not perfect and it must be ensured to adequately purge the adjacent cavity with sufficient cooling air to avoid hot gas ingestion. Reducing such uses of secondary air can increase gas turbine engine efficiency.
Accordingly, there is a need for an improved turbine shroud sealing arrangement.